In recent years, many industries have used silicon on insulator (SOI) substrate to manufacture a semiconductor integrated circuit instead of using a piece of a silicon wafer. Because using an SOI substrate has an advantage of reducing the parasitic capacitance between a drain and a substrate, whereby a performance of a semiconductor integrated circuit can be promoted.
With regard to a method for manufacturing a semiconductor device, such as U.S. Pat. No. 5,374,564, which provides a method for doping hydrogen ions into a silicon wafer, and forming an ion doped layer at a pre-determined depth of the silicon wafer. Then the silicon wafer doped by hydrogen ions is coupled with another silicon wafer, and a silicon oxide film is formed between the two silicon wafers. Then the two silicon wafers are separated at the ion doped layer by a heat treatment, whereby a monocrystalline silicon film can be formed on the ion doped layer.
For example, U.S. Pat. No. 5,872,387 provides a method for annealing a substrate growth, a gate oxide layer at a deuterium atmosphere, whereby dangling bonds between the gate oxide and the substrate can be removed. However, this method should be proceeding at a very high deuterium pressure, so that a cost for manufacturing a semiconductor device is increased.
In view of prior arts described above, an improved method is needed for manufacturing a SOI substrate, which at least solves drawbacks described above.